The present invention relates to an operational amplifier circuit, and to means, which enables an operational amplifier to exhibit a nearly infinite open loop gain without bandwidth degradation.
Operational Amplifiers are used in many electronic applications requiring high sensitivity or accuracy such as instrumentation amplifiers and sensor or detection applications. For these applications, operational amplifier circuits are designed with high gain to provide high sensitivity or accuracy. Yet, as performance improvements in such electronics applications are desirable, so are improvements in the open loop gain of an operational amplifier are desirable.
In accordance with the present invention, there is disclosed an operational amplifier circuit with a bi-directional cascode current amplifier. The bi-directional cascode current amplifier filters out the common-mode signal resulting in a nearly infinite open loop gain without bandwidth degradation.